1. Field of the Invention
The present invention relates to insoluble, only slightly swellable polymers having modified amino groups, processes for the preparation of such polymers and the use of the insoluble, only slightly swellable polymers having modified amino groups as adsorber resin for metal ions and ion exchangers.
2. Description of the Background
DE-A-23 03 081 discloses the preparation of water-soluble reaction products of polyethyleneimine with the sodium salt of chloroacetic acid in aqueous solution. Water-soluble polyethyleneimines having iminodiacetic acid groups are obtained. The water-soluble polymers are used as complexing agents for metal ions.
U.S. Pat. No. 3,424,790 discloses the preparation of water-soluble, carboxymethylated polyethyleneimines by a multistage process. First, equivalent amounts of polyethyleneimine are reacted with formaldehyde at from -15 to 40.degree. C. Thereafter, the adduct is reacted with hydrogen cyanide or alkali metal cyanides, likewise at from -15 to 40.degree. C., and the reaction products are hydrolyzed with alkali metal hydroxides at from 50 to 110.degree. C. in a subsequent reaction stage. EP-B-071 050 discloses partially hydrolyzed polymers of N-vinylformamide which contains from 90 to 10 mol % of vinylamine units and from 10 to 90 mol % of N-vinylformamide units. EP-A-0 216 387 describes copolymers of N-vinylformamide with other ethylenically unsaturated monomers. The polymerized N-vinylformamide units can be converted into vinylamine units by hydrolysis with acids or bases. Polymers containing vinylamine units are furthermore described in EP-A-0 262 577, EP-A-264 649 and EP-A-0 251 182.
WO-A-94/11408 discloses insoluble, only slightly swellable polymers which contain polymerized vinylamine units. These polymers are prepared by polymerizing N-vinylcarboxamides and, if required, other monoethylenically unsaturated monomers copolymerizable with said N-vinylcarboxamides with, as crosslinking agents, compounds containing at least two ethylenically unsaturated double bonds, in the absence of oxygen and polymerization initiators, to give popcorn polymers, and then hydrolyzing the polymerized N-vinylcarboxamide units to give vinylamine units by the action of acids, bases or enzymes. The amino-containing popcorn polymers are used as ion exchangers or as adsorber resin for metal ions. The polymers described above and containing N-vinylglycine or N-vinyliminodiacetic acid units are water-soluble. If they are used as complexing agents for metal ions dissolved in water, expensive technology is required for separating the polymeric complexes from the solution.